iOS开发小知识点

http://www.cnblogs.com/tangbinblog/archive/2012/07/20/2601324.html

Objective-C中的instancetype和id区别

http://blog.csdn.net/kuizhang1/article/details/18048829

IOS开发笔记之绘图（CGContext小记）

http://blog.sina.com.cn/s/blog_7a162d000101dag2.html

http://www.cnblogs.com/y041039/archive/2012/07/11/2586629.html

http://www.cnblogs.com/maomishen/p/4924726.html

http://www.cnblogs.com/mtjbz/p/4945006.html